Cell culture media in aqueous solution can provide an environment which supports and maintains the growth of cells and/or maintains a desired physiological cellular condition adventitious to the targeted production of certain products.
Cell culture media comprise of a complex mixture of components, sometimes more than one hundred different components, depending on the type of organism whose growth and/or targeted physiological status shall be supported.
The cell culture media required for the propagation of mammalian, insect or plant cells are typically much more complex than the media to support the growth of bacteria, yeast or fungi.
The first cell culture media that were developed consisted of undefined components, such as plasma, serum, embryo extracts, or other non-defined biological extracts or peptones. A major advance was thus made with the development of chemically defined media. Chemically defined media often comprise but are not exclusively limited to amino acids, vitamins, metal salts, antioxidants, chelators, growth factors, buffers, hormones, and many more substances known to those expert in the art.
Some cell culture media are offered as sterile aqueous liquids. The disadvantage of liquid cell culture media is their reduced shelf life and difficulties for shipping and storage. As a consequence, many cell culture media are presently offered as finely milled dry powder mixtures. They are manufactured for the purpose of dissolving in water and/or aqueous solutions and in the dissolved state are designed, often with other supplements, for supplying cells with a substantial nutrient base for growth and/or production of biopharmaceuticals from same said cells.
The production of cell culture media in the form of powders is very critical. Powdered media are typically produced by admixing the dried components of the culture medium via a mixing and milling process, e.g., ball-milling.
In milling processes on the other hand it is often difficult to generate homogenous mixtures as the ingredients with up to 9 orders of magnitude difference in concentration need to be homogenized. That means components of which less than a microgram is present in one kilogram of a media composition need to be homogenously distributed in the cell culture medium.
It has been tried to overcome those difficulties by lyophilizing a pre-made liquid culture medium. However, in a lyophilisation process some of the components of the medium might become insoluble or aggregate upon lyophilization such that resolubilization is difficult or impossible. Additionally, many of the media supplements, particularly serum supplements such as FBS, show a substantial loss of activity or are rendered completely inactive if attempts are made to produce powdered supplements by processes such as lyophilization.
Consequently, there exists a clear need for finding an improved process for manufacturing powdered cell culture media that do not have the disadvantages mentioned above.